Transforming non-contiguous instruction specifiers to contiguous instruction specifiers

ABSTRACT

Emulation of instructions that include non-contiguous specifiers is facilitated. A non-contiguous specifier specifies a resource of an instruction, such as a register, using multiple fields of the instruction. For example, multiple fields of the instruction (e.g., two fields) include bits that together designate a particular register to be used by the instruction. Non-contiguous specifiers of instructions defined in one computer system architecture are transformed to contiguous specifiers usable by instructions defined in another computer system architecture. The instructions defined in the another computer system architecture emulate the instructions defined for the one computer system architecture.

BACKGROUND

An aspect of the invention relates, in general, to emulation within acomputing environment, and in particular, to emulation of specifierswithin instructions.

Emulation imitates functions on a computer architecture, referred to asa target architecture. The target architecture differs from a computerarchitecture, referred to as a source architecture, for which thefunctions were defined. For instance, an instruction written for thez/Architecture provided by International Business Machines Corporation,Armonk, N.Y., may be translated and represented as one or moreinstructions of a different architecture, such as PowerPC, also offeredby International Business Machines Corporation, or another architectureoffered by International Business Machines Corporation or anothercompany. These translated instructions perform the same or a similarfunction as the instruction being translated.

There are different types of emulation, including interpretation andtranslation. With interpretation, data representing an instruction isread, and as each instruction is decoded, it is executed. Eachinstruction is executed each time it is referenced. However, withtranslation, also referred to as binary translation or recompilation,sequences of instructions are translated from the instruction set of onecomputer architecture to the instruction set of another computerarchitecture.

There are multiple types of translation, including static translationand dynamic translation. In static translation, code of an instructionof the one architecture is converted to code that runs on the otherarchitecture without previously executing the code. In contrast, indynamic translation, at least a section of the code is executed andtranslated, and the result is placed in a cache for subsequent executionby a processor of the target computer architecture.

BRIEF SUMMARY

Shortcomings of the prior art are overcome and advantages are providedthrough the provision of a computer program product for transforminginstruction specifiers of a computing environment. The computer programproduct includes a computer readable storage medium readable by aprocessing circuit and storing instructions for execution by theprocessing circuit for performing a method including: obtaining, by aprocessor, from a first instruction defined for a first computerarchitecture, a non-contiguous specifier, the non-contiguous specifierhaving a first portion and a second portion, wherein the obtainingincludes obtaining the first portion from a first field of theinstruction and the second portion from a second field of theinstruction, the first field separate from the second field; generatinga contiguous specifier using the first portion and the second portion,the generating using one or more rules based on the opcode of the firstinstruction; and using the contiguous specifier to indicate a resourceto be used in execution of a second instruction, the second instructiondefined for a second computer architecture different from the firstcomputer architecture and emulating a function of the first instruction.

Methods and systems relating to one or more aspects of the presentinvention are also described and claimed herein. Further, servicesrelating to one or more aspects of the present invention are alsodescribed and may be claimed herein.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and objects, features, andadvantages of one or more aspects of the invention are apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 depicts one example of a computing environment to incorporate anduse one or more aspects of the present invention;

FIG. 2 depicts further details of the memory of FIG. 1, in accordancewith an aspect of the present invention;

FIG. 3 depicts one embodiment of an overview of an emulation processthat employs one or more of interpretation and translation;

FIG. 4 depicts one example of logic associated with the interpretationblock referenced in FIG. 3;

FIG. 5 depicts one example of logic associated with the translationblock referenced in FIG. 3;

FIG. 6 depicts another embodiment of an overview of an emulation processthat employs one or more of interpretation and translation modified inaccordance with an aspect of the present invention;

FIG. 7A depicts one example of logic associated with the interpretationblock referenced in FIG. 6, in accordance with an aspect of the presentinvention;

FIG. 7B depicts one embodiment of the logic to transform anon-contiguous specifier to a contiguous specifier, in accordance withan aspect of the present invention;

FIG. 8 depicts one example of logic associated with the translationblock referenced in FIG. 6, in accordance with an aspect of the presentinvention;

FIG. 9A depicts one embodiment of transforming a non-contiguousspecifier in a Vector Load instruction of one computer architecture to acontiguous specifier in a Load Vector Indexed instruction of anothercomputer architecture, in accordance with an aspect of the presentinvention;

FIG. 9B depicts another example of the transformation of FIG. 9A,including allocation of a particular register to the contiguousspecifier, in accordance with an aspect of the present invention;

FIG. 10 depicts one example of a register file, in accordance with anaspect of the present invention;

FIG. 11 depicts an example of transforming non-contiguous specifiers tocontiguous specifiers in allocating to memory during emulation, inaccordance with an aspect of the present invention;

FIG. 12 depicts one embodiment of a computer program productincorporating one or more aspects of the present invention;

FIG. 13 depicts one embodiment of a host computer system to incorporateand use one or more aspects of the present invention;

FIG. 14 depicts a further example of a computer system to incorporateand use one or more aspects of the present invention;

FIG. 15 depicts another example of a computer system comprising acomputer network to incorporate and use one or more aspects of thepresent invention;

FIG. 16 depicts one embodiment of various elements of a computer systemto incorporate and use one or more aspects of the present invention;

FIG. 17A depicts one embodiment of the execution unit of the computersystem of FIG. 16 to incorporate and use one or more aspects of thepresent invention;

FIG. 17B depicts one embodiment of the branch unit of the computersystem of FIG. 16 to incorporate and use one or more aspects of thepresent invention;

FIG. 17C depicts one embodiment of the load/store unit of the computersystem of FIG. 16 to incorporate and use one or more aspects of thepresent invention; and

FIG. 18 depicts one embodiment of an emulated host computer system toincorporate and use one or more aspects of the present invention.

DETAILED DESCRIPTION

In accordance with an aspect of the present invention, a technique isprovided for facilitating emulation of instructions that includenon-contiguous specifiers. A non-contiguous specifier specifies aresource of an instruction, such as a register, using multiple fields ofthe instruction. For example, multiple fields of the instruction (e.g.,two fields) include bits that together designate a particular registerto be used by the instruction.

In a particular aspect of the invention, a technique is provided fortransforming non-contiguous specifiers of instructions defined in onecomputer system architecture (e.g., the z/Architecture offered byInternational Business Machines Corporation) to contiguous specifiersusable by instructions defined in another computer system architecture(e.g., the PowerPC architecture offered by International BusinessMachines Corporation). The instructions defined in the another computersystem architecture emulate the instructions defined for the onecomputer system architecture.

One embodiment of a computing environment providing emulation isdescribed with reference to FIG. 1. In one example, a computingenvironment 100 includes, for instance, a native central processing unit102, a memory 104, and one or more input/output devices and/orinterfaces 106 coupled to one another via, for example, one or morebuses 108 and/or other connections. As examples, computing environment100 may include a PowerPC processor, a pSeries server or an xSeriesserver offered by International Business Machines Corporation, Armonk,N.Y.; an HP Superdome with Intel Itanium II processors offered byHewlett Packard Co., Palo Alto, Calif.; and/or other machines based onarchitectures offered by International Business Machines Corporation,Hewlett Packard, Intel, Oracle, or others.

Native central processing unit 102 includes one or more native registers110, such as one or more general purpose registers and/or one or morespecial purpose registers used during processing within the environment.These registers include information that represents the state of theenvironment at any particular point in time.

Moreover, native central processing unit 102 executes instructions andcode that are stored in memory 104. In one particular example, thecentral processing unit executes emulator code 112 stored in memory 104.This code enables the processing environment configured in onearchitecture to emulate another architecture. For instance, emulatorcode 112 allows machines based on architectures other than thez/Architecture, such as PowerPC processors, pSeries servers, xSeriesservers, HP Superdome servers or others, to emulate the z/Architectureand to execute software and instructions developed based on thez/Architecture.

Further details relating to emulator code 112 are described withreference to FIG. 2. Guest instructions 200 comprise softwareinstructions (e.g., machine instructions) that were developed to beexecuted in an architecture other than that of native CPU 102. Forexample, guest instructions 200 may have been designed to execute on az/Architecture processor, but instead, are being emulated on native CPU102, which may be, for example, a PowerPC processor or other type ofprocessor. In one example, emulator code 112 includes an instructionfetching unit 202 to obtain one or more guest instructions 200 frommemory 104, and to optionally provide local buffering for theinstructions obtained. It also includes an instruction translationroutine 204 to determine the type of guest instruction that has beenobtained and to translate the guest instruction into one or morecorresponding native instructions 206. This translation includes, forinstance, identifying the function to be performed by the guestinstruction (e.g., via the opcode) and choosing the nativeinstruction(s) to perform that function.

Further, emulator 112 includes an emulation control routine 210 to causethe native instructions to be executed. Emulation control routine 210may cause native CPU 102 to execute a routine of native instructionsthat emulate one or more previously obtained guest instructions and, atthe conclusion of such execution, return control to the instructionfetch routine to emulate the obtaining of the next guest instruction ora group of guest instructions. Execution of the native instructions 206may include loading data into a register from memory 104; storing databack to memory from a register; or performing some type of arithmetic orlogic operation, as determined by the translation routine.

Each routine is, for instance, implemented in software, which is storedin memory and executed by native central processing unit 102. In otherexamples, one or more of the routines or operations are implemented infirmware, hardware, software or some combination thereof. The registersof the emulated processor may be emulated using registers 110 of thenative CPU or by using locations in memory 104. In embodiments, guestinstructions 200, native instructions 206 and emulator code 112 mayreside in the same memory or may be disbursed among different memorydevices.

As used herein, firmware includes, e.g., the microcode, millicode and/ormacrocode of the processor. It includes, for instance, thehardware-level instructions and/or data structures used inimplementation of higher level machine code. In one embodiment, itincludes, for instance, proprietary code that is typically delivered asmicrocode that includes trusted software or microcode specific to theunderlying hardware and controls operating system access to the systemhardware.

In one example, a guest instruction 200 that is obtained, translated andexecuted is one or more of the instructions described herein. Theinstruction, which is of one architecture (e.g., the z/Architecture) isfetched from memory, translated and represented as a sequence of nativeinstructions 206 of another architecture (e.g., PowerPC, pSeries,xSeries, Intel, etc.). These native instructions are then executed.

Further details regarding emulation are described with reference toFIGS. 3-5. In particular, FIG. 3 depicts one embodiment of an overviewof an emulation process that employs one or more of interpretation andtranslation; FIG. 4 depicts one embodiment of the logic associated withinterpretation referenced in FIG. 3 (Technique 2000); and FIG. 5 depictsone embodiment of the logic associated with binary translationreferenced in FIG. 3 (Technique 3000). In this particular example,instructions written for the z/Architecture are being translated toPowerPC instructions. However, the same techniques are applicable foremulation from the z/Architecture to other target architectures; fromother source architectures to the PowerPC architecture; and/or fromother source architectures to other target architectures.

Referring to FIG. 3, during emulation, an instruction, referred to asinstruction X, is obtained and interpreted, as described in furtherdetail with reference to FIG. 4, STEP 300. Various statistics relatingto the interpreted instruction are updated, STEP 302, and thenprocessing proceeds to the next instruction, which becomes instruction Xin the logic, STEP 304. A determination is made as to whether this nextinstruction has a previous translated entry point, INQUIRY 306. If not,a further determination is made as to whether this next instruction hasbeen seen N (e.g., 15) times, INQUIRY 308. That is, has this instructionbeen seen often enough in order to optimize execution by, for instance,performing just-in-time (JIT) compilation of the code, which provides anentry point for subsequent use. If this instruction has not been seen Ntimes, such as 15 times, then processing continues with STEP 300.Otherwise, processing continues with forming a group of instructions andtranslating the group of instructions from one architecture to anotherarchitecture, STEP 310. One example of performing this translation isdescribed with reference to FIG. 5. Subsequent to forming andtranslating the group, the group is executed, STEP 312, and processingcontinues to STEP 304.

Returning to INQUIRY 306, if there is an existing translated entry pointfor the instruction, processing continues with executing the group atthe entry point, STEP 312.

Further details relating to interpreting an instruction (Technique 2000)are described with reference to FIG. 4. Initially, an instruction at thenext program counter (PC) address is read, STEP 400. This instruction isanalyzed, and opcode, register and immediate fields are extracted, STEP402. Then, a branch is performed to the code that emulates behaviorcorresponding to the extracted opcode, STEP 404. The emulated code isthen performed, STEP 406.

Further details regarding translating instructions within a group(Technique 3000) are described with reference to FIG. 5. Initially, aninstruction in a pre-defined group of instructions is read, STEP 500. Inone example, the group can be formed using a variety of ways. Inaccordance with one embodiment, a group is formed to encompass a singlepath of execution along a most likely path. In another embodiment, agroup is formed to encompass one of the last previous execution paths,or the current execution path, based on the emulated architecture'sstate. In another embodiment, all branches are assumed not taken. In yetanother embodiment, multiple paths are included in a group, such as allpaths starting from the group starting point. In another embodiment, allinstructions up to and including the first branch are added to a group(i.e., a group corresponds to a straight line piece of code alsocommonly known as a “basic block”). In each embodiment, a decision hasto be made as to when and where to end a group. In one embodiment, agroup is ended after a fixed number of instructions. In anotherembodiment, the group is ended after a cumulative probability ofreaching an instruction is below a given threshold. In some embodiments,a group is stopped immediately when a stopping condition has beenreached. In another set of embodiments, a group is stopped only at awell-defined “stopping point”, e.g., a defined instruction, a specificgroup start alignment, or other condition.

Thereafter, the instruction is analyzed, and opcode, register andimmediate fields are extracted from the instruction, STEP 502. Next, aninternal representation of the extracted information is provided, STEP504. This internal representation is a format of the extractedinformation that is used by the processor (e.g., compiler or translator)to optimize decoding, register allocation, and/or other tasks associatedwith translating the instruction.

Further, a determination is made as to whether there is anotherinstruction in the group to be translated, INQUIRY 506. If so, thenprocessing continues with STEP 500. Otherwise, processing continues withoptimizing the internal representation, STEP 508, allocating one or moreregisters for the group of instructions, STEP 510, and generating codethat emulates the instructions in the group, STEP 512.

While the above interpretation and translation procedures provide foremulation of an instruction defined in one architecture to one or moreinstructions defined in another architecture, advancements may be madein the emulation of instructions that use non-contiguous specifiers. Forinstance, in accordance with an aspect of the present invention,improvements in emulation techniques are provided to address thesituation in which a register operand of an instruction is designated bymultiple fields of the instruction.

One type of instruction that uses non-contiguous specifiers is vectorinstructions that are part of a vector facility, provided in accordancewith an aspect of the present invention. In many vector instructions,the register field does not include all of the bits needed to designatea register to be used by the instruction, but instead, another field isused along with the register field to designate a register. This otherfield is referred to herein as an RXB field.

The RXB field, also referred to as the register extension bit, is, forinstance, a four bit field (bits 0-3) that includes the most significantbit for each of the vector register designated operands of a vectorinstruction. Bits for register designations not specified by theinstruction are to be reserved and set to zero.

In one example, the RXB bits are defined as follows:

-   -   0—Most significant bit for the first vector register designation        of the instruction.    -   1—Most significant bit for the second vector register        designation of the instruction, if any.    -   2—Most significant bit for the third vector register designation        of the instruction, if any.    -   3—Most significant bit for the fourth vector register        designation of the instruction, if any.

Each bit is set to zero or one by, for instance, the assembler dependingon the register number. For instance, for registers 0-15, the bit is setto 0; for registers 16-31, the bit is set to 1, etc.

In one embodiment, each RXB bit is an extension bit for a particularlocation in an instruction that includes one or more vector registers.For instance, in one or more vector instructions, bit 0 of RXB is anextension bit for location 8-11, which is assigned to e.g., V₁; bit 1 ofRXB is an extension bit for location 12-15, which is assigned to, e.g.,V₂; and so forth.

In a further embodiment, the RXB field includes additional bits, andmore than one bit is used as an extension for each vector or location.

In accordance with an aspect of the present invention, techniques areprovided for transforming non-contiguous operand specifiers intocontiguous specifiers. Once transformed, the contiguous specifiers areused without any regard to the non-contiguous specifiers.

One embodiment of the logic to emulate instructions that usenon-contiguous specifiers is described with reference to FIGS. 6-8. Inparticular, FIG. 6 depicts an overview of an emulation process includingone or more of interpretation and translation of instructions thatinclude non-contiguous specifiers; FIG. 7A depicts one embodiment ofinterpretation (Technique 6000), including interpretation ofnon-contiguous specifiers; FIG. 7B depicts one embodiment oftransforming a non-contiguous specifier to a contiguous specifier; andFIG. 8 depicts one embodiment of translation (Technique 7000), includingtranslation of non-contiguous specifiers.

Referring initially to FIG. 6, an overview of an emulation process isprovided. This overview is similar to the overview provided in FIG. 3,except STEP 600 uses Technique 6000 described with reference to FIG. 7A,instead of Technique 2000 referenced in STEP 300; and STEP 610 usesTechnique 7000 described with reference to FIG. 8, instead of Technique3000 referenced in STEP 310. Since the overview is described above withreference to FIG. 3, it is not repeated here; instead, the discussionproceeds to the logic of FIG. 7A.

Referring to FIG. 7A, STEPS 700, 702, 704 and 706 are similar to STEPs400, 402, 404 and 406, respectively, of FIG. 4, and therefore, are notdescribed again; however, STEPs 703 and 705 are described. With STEP703, in accordance with an aspect of the present invention, a contiguousspecifier (also referred to herein as a contiguous index) is generatedfrom a non-contiguous specifier. Further details regarding generation ofa contiguous specifier from a non-contiguous specifier are describedwith reference to FIG. 7B.

Referring to FIG. 7B, in one embodiment, initially, the non-contiguousspecifier is obtained, STEP 750. This includes, for instance,determining from the opcode that the instruction has a non-contiguousspecifier and determining which fields of the instruction are used todesignate the non-contiguous specifier. For instance, a portion of theopcode specifies a format of the instruction and this format indicatesto the processor that the instruction has at least one non-contiguousspecifier and it further specifies the fields used to designate thenon-contiguous specifier. These fields are then read to obtain the data(e.g., bits) in those fields. For instance, in many vector instructions,location 8-11 of the instruction (e.g., V₁) specifies a plurality ofbits (e.g., 4) used to designate a vector register, and an RXB field ofthe instruction includes one or more additional bits used to designatethe particular vector register. These bits are obtained in this step.

Subsequent to obtaining the non-contiguous specifier (e.g., bits fromregister field V₁ and bit(s) from RXB), one or more rules are used tocombine the portions of the non-contiguous specifier to create thecontiguous specifier, STEP 752. The one or more rules depend, forinstance, on the format of the instruction as specified by the opcode ofthe instruction. In a particular example in which the opcode indicatesan RXB field, the one or more rules include using the RXB bit(s)associated with the register operand as the most significant bit(s) forthe bits specified in the register field. For instance, the RXB fieldhas, in one embodiment, 4 bits and each bit corresponds to a registeroperand. For instance, bit 0 corresponds to the first register operand,bit 1 corresponds to the second register operand, and so forth. So, thebit corresponding to the register operand is extracted and used to formthe contiguous specifier. For example, if 0010 binary is specified inthe first operand register field and 1000 binary is specified in the RXBfield, the value of the bit associated with the first operand, bit 0, inthis example, is concatenated to 0010. Therefore, the contiguousspecifier is 10010 (register 18), in this example.

The generated contiguous specifier is then used as if it was thespecifier provided in the instruction, STEP 754.

Thereafter, returning to FIG. 7A, a branch is performed to code thatemulates the behavior corresponding to the opcode, STEP 704. Further,the contiguous index is used to manage the homogenized architectureresource without regard to the non-contiguous specifier, STEP 705. Thatis, the contiguous register specifier is used, as if there was nonon-contiguous specifier. Each contiguous specifier indicates a registerto be used by the emulation code. Thereafter, the emulation code isperformed, STEP 706.

Further details regarding translation including the transforming ofnon-contiguous specifiers to contiguous specifiers (referred to asTechnique 7000) are described with reference to FIG. 8. In oneembodiment, STEPS 800, 802, 804, 806, 808, 810 and 812 are similar toSTEPS 500, 502, 504, 506, 508, 510, and 512, respectively, of FIG. 5,and therefore, are not described here with reference to FIG. 8. However,in accordance with an aspect of the present invention, further steps areperformed in order to transform a non-contiguous specifier of aninstruction of a source architecture to a contiguous specifier of aninstruction of a target architecture. The instruction of the targetarchitecture emulates a function of the instruction of the sourcearchitecture.

For example, in STEP 803, a contiguous specifier is generated from anon-contiguous specifier. As described above with reference to FIG. 7B,this includes obtaining the non-contiguous specifier from theinstruction to be emulated, and using one or more rules to create thecontiguous specifier from the non-contiguous specifier. In oneembodiment, the opcode of the instruction that has the non-contiguousspecifier indicates, at least implicitly by its format, that theinstruction includes a non-contiguous specifier. For instance, theformat of the instruction is indicated by one or more bits of the opcode(e.g., the first two bits), and based on the format, the processor(e.g., the compiler, translator, emulator of the processor) understandsthat this instruction includes a non-contiguous specifier, in which partof the specifier of a resource, such as a register, is included in onefield of the instruction and one or more other parts of the specifierare located in one or more other fields of the instruction.

The opcode, as an example, also provides an indication to the processorof the one or more rules used to generate the contiguous specifier fromthe non-contiguous specifier. For instance, the opcode may indicate thata particular instruction is a vector register instruction, and thus, hasan RXB field. Therefore, the processor accesses information (e.g., rulesstored in memory or external storage) that indicates for an instructionwith an RXB field, the RXB field provides the most significant bit forits corresponding register field. The rules specify, for instance, thatto generate the contiguous field, the bits of the register field arecombined with the one or more bits of the RXB field associated with theparticular register operand.

Subsequent to generating the contiguous specifier, the contiguousspecifier is used without regard to the non-contiguous specifier. Forinstance, in STEP 808, the code is optimized using the contiguousspecifier without regard to the non-contiguous specifier. Similarly, oneor more registers are allocated using the contiguous specifier andwithout regard to the non-contiguous specifier, STEP 810. Yet further,in STEP 812, the emulated code is generated without regard to thenon-contiguous specifier and using the allocation performed in STEP 810.That is, in these steps, there is no indication that the contiguousspecifier was generated from a non-contiguous specifier. Thenon-contiguous specifier is ignored.

Further details regarding translating a non-contiguous specifier to acontiguous specifier are described with reference to the examples inFIGS. 9A, 9B and 11. Referring initially to FIG. 9A, a Vector Load (VL)instruction 900 is depicted. In one example, the Vector Load instructionincludes opcode fields 902 a (e.g., bits 0-7), 902 b (e.g., bits 40-47)indicating a vector load operation; a vector register field 904 (e.g.,bits 8-11) used to designate a vector register (V₁); an index field (X₂)906 (e.g., bits 12-15); a base field (B₂) 908 (e.g., bits 16-19); adisplacement field (D₂) 910 (e.g., bits 20-31); and an RXB field 912(e.g., bits 36-39). Each of the fields 904-912 in one example isseparate and independent from the opcode field(s). Further, in oneembodiment they are separate and independent from one another; howeverin other embodiments, more than one field may be combined. Furtherinformation on the use of these fields is described below.

In one example, selected bits (e.g., the first two bits of the opcodedesignated by opcode field 902 a) specify the length and format of theinstruction. In this particular example, the length is three half-wordsand the format is a vector register-and-index storage operation with anextended opcode field. The vector (V₁) field, along with itscorresponding extension bit specified by RXB, designates a vectorregister (i.e., a non-contiguous specifier). In particular, for vectorregisters, the register containing the operand is specified using, forinstance, a four-bit field of the register field with the addition ofits register extension bit (RXB) as the most significant bit. Forinstance, if the four bit field in V₁ is 0010 binary and the extensionbit for this operand is 1 binary, then the 5-bit field is 10010 binary,indicating register number 18 (in decimal).

The subscript number associated with the field of the instructiondenotes the operand to which the field applies. For instance, thesubscript number 1 associated with V₁ denotes the first operand, and soforth. This is used to determine which bit of the RXB field is combinedwith the register field. The register operand is one register in length,which is for instance, 128 bytes. In one example, in a vectorregister-and-index storage operation instruction, the contents ofgeneral registers designated by the X₂ and B₂ fields are added to thecontents of the D₂ field to form the second operand address. Thedisplacement, D₂, for the Vector Load instruction is treated as a 12-bitunsigned integer, in one example.

In this example, since V₁ is the first operand, the leftmost location(e.g., bit 0) of the RXB is associated with this operand. Therefore, thevalue located in the leftmost location is combined with the value in theV₁ register field to generate the contiguous specifier, as describedherein.

In accordance with an aspect of the present invention, the Vector Loadinstruction 900, which is defined, for instance, in the z/Architecture,is emulated into a Load Vector Indexed instruction 950 defined, forinstance, in the PowerPC architecture. Although, in this example, thez/Architecture is the source architecture and PowerPC is the targetarchitecture, this is only one example. Many other architectures may beused for one or both of the source and target architectures.

Each architecture has associated with it particular registers that itmay use. For instance, in the z/Architecture, there are 32 vectorregisters and other types of registers can map to a quadrant of thevector registers. As an example, as shown in FIG. 10, if there is aregister file 1000 that includes 32 vector registers 1002 and eachregister is 128 bits in length, then 16 floating point registers 1004,which are 64 bits in length, can overlay the vector registers. Thus, asan example, when floating point register 2 is modified, then vectorregister 2 is also modified. Other mappings for other types of registersare also possible.

Similarly, the PowerPC or other target architecture has a set ofregisters assigned to it. This set of registers may be different or thesame as the set of registers allocated to the source architecture. Thetarget register may have more or less registers available for aparticular type of instruction. For instance, in the example depicted inFIG. 9A, the Vector Load instruction and the Load Vector Indexedinstruction have 32 vector registers available to it. Again, otherexamples are possible.

As indicated by the opcode, the Vector Load instruction includes anon-contiguous specifier, which in this example, is represented in theV₁ and RXB fields. These non-contiguous fields are combined to create acontiguous index in the Load Vector Indexed instruction 950. Thiscontiguous specifier is indicated in VRT field 954 of instruction 950.In this particular example, as shown in the code VL v18, 0(0, gr5), thevector register being specified is register 18. This register isspecified in the instruction by the non-contiguous specifier provided bythe V₁ field and the RXB field. In this example, the V1 field includes avalue of 2 (0010 binary) and the RXB field includes a value of 8 (1000binary). Based on the pre-defined rules, since V₁ is the first operand,the leftmost bit (1) of 1000 is concatenated with the bits in the V1field (0010) to produce a contiguous specifier of 10010, which is thevalue 18 in decimal.

As shown at reference numeral 956, a representation of 18 is placed inthe VRT field of the Load Vector Indexed instruction, which correspondsto the register field (V₁) of the Vector Load instruction. Forcompleteness, the RA and RB fields of instruction 950 correspond to theX₂ and B₂, respectively, of instruction 900. The D₂ field of instruction900 has no corresponding field in instruction 950; and the opcode fieldsof instruction 900 correspond to the opcode fields of instruction 950.

A further example is depicted in FIG. 9B. In this example, as with theexample depicted in FIG. 9A, the non-contiguous specifier (V₁, RXB) ofinstruction 900 is being transformed into a contiguous specifier (VRT)of instruction 950. However, in this example, the register allocated forinstruction 950 does not have the same number as the transformedcontiguous specifier; instead, the contiguous specifier is mapped to adifferent register. For instance, in the example in FIG. 9A, thenon-contiguous specifier references register 18, as does the contiguousspecifier. That is, there is a one for one mapping. However, in FIG. 9B,the non-contiguous specifier of 18 is transformed into a contiguousspecifier of 18, but then, the 18 of the contiguous specifier is mappedto a different register, such as register 7 (see reference number 980).That is, register 18 in the source architecture maps to register 7 inthe target architecture, in this particular example. Such a mapping ispre-defined and accessible to the processor.

A yet further example is depicted in FIG. 11. In this example, insteadof allocating to a register during emulation, as in FIGS. 9A and 9B,allocation is to memory. In this example, an instruction, VLR, is usedto move the contents of one vector register, VR 18, to another vectorregister, VR 24. However, in this example, it is assumed that theregister file is not large enough to include these vector registers, somemory is used, instead. That is, there is a contiguous portion ofmemory that stores a plurality of vectors as an array. The array startsat an address, rvbase, at which the first register, e.g., register 0, isstored; and then, the next register is stored at an offset, e.g., 16bytes, from rvbase; and the third register is stored at the offset fromthe second register, and so forth. Thus, in this example, register 18 isat an offset 288 from rvbase, and register 24 is at an offset 384 fromrvbase.

In this example, there are two non-contiguous specifiers (V₁, RXB; andV₂, RXB). Thus, two contiguous specifiers are generated. For instance,since V₁ is the first operand, the first contiguous specifier isgenerated by a concatenation of the bits in V₁ with bit 0 of RXB. SinceV₁ includes 1000 in binary (8 decimal) and RXB includes 1100 in binary(12 decimal), the first contiguous specifier is formed by concatenating1 (from bit 0 of RXB) with 1000 (from V₁) providing 11000 (24 indecimal). Similarly, the second contiguous specifier is generated by aconcatenation of 0010 (2 in decimal for V₂) and 1 (from bit 1 of RXB)providing 10010 (18 in decimal). Since these registers are withinmemory, vector register 24 is at an offset 384 from rvbase, and vectorregister 18 is at an offset 288 from rvbase. These values are shown inFIG. 11 at 1102, 1104, respectively.

The pseudo-code on the right of FIG. 11 and the instructions on the leftdescribe moving a contiguous number of bytes that correspond to a vectorregister at a vector offset at 18 (which corresponds to a byte offset at288) to a vector offset at 24 (which corresponds to a byte offset at384). In particular, a load immediate (LI) loads a value of 288 intortemp1, and then a vector load is performed at an address provided byrvbase plus the offset in rtemp1, and the value is stored in a temporaryvector register, vtemp2. Then, the next load immediate loads 384 intortemp1, and a store back out to memory is performed at a location thatcorresponds to the address plus offset in vector register 24 (e.g.,offset 288).

Although various examples are described above, many other examples andvariations are possible. Additional information regarding vectorinstructions and use of the RXB field is described in a patentapplication co-filed herewith, entitled “Instruction to Load Data Up toA Specified Memory Boundary Indicated by the Instruction,” U.S. Ser. No.13/421,456, Jonathan D. Bradbury et al., which is hereby incorporatedherein by reference in its entirety.

Further, various architectures are mentioned herein. One embodiment ofthe z/Architecture is described in an IBM® publication entitled,“z/Architecture Principles of Operation,” IBM® Publication No.SA22-7832-08, Ninth Edition, August, 2010, which is hereby incorporatedherein by reference in its entirety. IBM® and Z/ARCHITECTURE® areregistered trademarks of International Business Machines Corporation,Armonk, N.Y., USA. Other names used herein may be registered trademarks,trademarks, or product names of International Business MachinesCorporation or other companies. Additionally, one embodiment of thePower Architecture is described in “Power ISA™ Version 2.06 Revision B,”International Business Machines Corporation, Jul. 23, 2010, which ishereby incorporated herein by reference in its entirety. POWERARCHITECTURE® is a registered trademark of International BusinessMachines Corporation. Yet further, one embodiment of an Intelarchitecture is described in “Intel® 64 and IA-32 ArchitecturesDeveloper's Manual: Vol. 2B, Instructions Set Reference, A-L,” OrderNumber 253666-041US, December 2011, and “Intel® 64 and IA-32Architectures Developer's Manual: Vol. 2B, Instructions Set Reference,M-Z,” Order Number 253667-041US, December 2011, each of which is herebyincorporated herein by reference in its entirety. Intel® is a registeredtrademark of Intel Corporation, Santa Clara, Calif.

Described in detail herein is a technique for transformingnon-contiguous specifiers of an instruction defined for one systemarchitecture to contiguous specifiers for an instruction defined foranother system architecture. Previous architecture emulation has notsuccessfully addressed the emulation of systems with non-contiguousspecifiers, and particularly non-contiguous register specifiers, ineither fixed or variable width instruction sets. However, in accordancewith an aspect of the present invention, a technique is provided toextend prior emulators to handle non-contiguous specifiers. Thetechnique includes, for instance, reading non-contiguous specifiers,generating a contiguous index from a non-contiguous specifier, and usingthe contiguous index to access a homogeneous resource or represent ahomogeneous resource.

In a further embodiment, in accordance with a JIT implementation, acontiguous index is used to perform allocation decisions, optionallyrepresenting a resource accessed by a non-contiguous specifier by anon-contiguous/non-homogeneous resource, but not reflective ofpartitioning by non-contiguous specifier boundaries, but by optimizationdecisions. That is, in one embodiment, an instruction defined for onearchitecture has at least one non-contiguous specifier for at least oneresource, and that at least one non-contiguous specifier is transformedto at least one contiguous specifier. That at least one contiguousspecifier is used to select at least one resource for an instruction ofanother architecture to use. The instruction of the other architecture,however, uses non-contiguous specifiers. Thus, the at least onecontiguous specifier for the at least one selected resource is thentransformed into at least one non-contiguous specifier for use by theinstruction of the second architecture. In one embodiment, this isperformed by an emulator.

In one embodiment, an emulator is provided for emulating instructionexecution of a first computer architecture instruction set on aprocessor designed to a second computer architecture. The emulatorincludes, for instance, fetching instructions of an application by theemulation program; interpreting the opcode of the instructions in orderto select an emulation module for emulating the instructions;determining from the opcode that the instructions employ non-contiguousregister fields; combining non-contiguous register fields of theinstruction to form a combined register field; and using the combinedregister field by instructions of the emulation module, in order toemulate the instructions.

Further, in one embodiment, the register space includes a sub-section,and the first computer architecture instruction set includes firstinstructions having register fields for only accessing the sub-section,and second instructions having non-contiguous register fields foraccessing all of the register space.

In one embodiment, the RXB field is in the same location for all theinstructions using the RXB field. The RXB bits are bit significant inthat bit 36 of the RXB field is used to extend bits 8-11 of theinstruction; bit 37 of RXB is used to extend bits 12-15; bit 38 of RXBis used to extend bits 16-19; and bit 39 of RXB is used to extend bits32-35, as examples. Further, the decision to use a bit of the RXB as anextension bit is opcode dependent (e.g., R₁ vs. V₁). Moreover,non-contiguous specifiers can use fields other than RXB fields.

Herein, memory, main memory, storage and main storage are usedinterchangeably, unless otherwise noted explicitly or by context.

Additional details relating to the vector facility, including examplesof instructions, are provided as part of this Detailed Descriptionfurther below.

As will be appreciated by one skilled in the art, one or more aspects ofthe present invention may be embodied as a system, method or computerprogram product. Accordingly, one or more aspects of the presentinvention may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, resident software,micro-code, etc.) or an embodiment combining software and hardwareaspects that may all generally be referred to herein as a “circuit,”“module” or “system”. Furthermore, one or more aspects of the presentinvention may take the form of a computer program product embodied inone or more computer readable medium(s) having computer readable programcode embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readablestorage medium. A computer readable storage medium may be, for example,but not limited to, an electronic, magnetic, optical, electromagnetic,infrared or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples (a non-exhaustivelist) of the computer readable storage medium include the following: anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing. In the context of this document,a computer readable storage medium may be any tangible medium that cancontain or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Referring now to FIG. 12, in one example, a computer program product1200 includes, for instance, one or more non-transitory computerreadable storage media 1202 to store computer readable program codemeans or logic 1204 thereon to provide and facilitate one or moreaspects of the present invention.

Program code embodied on a computer readable medium may be transmittedusing an appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for one or moreaspects of the present invention may be written in any combination ofone or more programming languages, including an object orientedprogramming language, such as Java, Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language, assembler or similar programming languages. Theprogram code may execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

One or more aspects of the present invention are described herein withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the invention. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of one or more aspects of the present invention. In thisregard, each block in the flowchart or block diagrams may represent amodule, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

In addition to the above, one or more aspects of the present inventionmay be provided, offered, deployed, managed, serviced, etc. by a serviceprovider who offers management of customer environments. For instance,the service provider can create, maintain, support, etc. computer codeand/or a computer infrastructure that performs one or more aspects ofthe present invention for one or more customers. In return, the serviceprovider may receive payment from the customer under a subscriptionand/or fee agreement, as examples. Additionally or alternatively, theservice provider may receive payment from the sale of advertisingcontent to one or more third parties.

In one aspect of the present invention, an application may be deployedfor performing one or more aspects of the present invention. As oneexample, the deploying of an application comprises providing computerinfrastructure operable to perform one or more aspects of the presentinvention.

As a further aspect of the present invention, a computing infrastructuremay be deployed comprising integrating computer readable code into acomputing system, in which the code in combination with the computingsystem is capable of performing one or more aspects of the presentinvention.

As yet a further aspect of the present invention, a process forintegrating computing infrastructure comprising integrating computerreadable code into a computer system may be provided. The computersystem comprises a computer readable medium, in which the computermedium comprises one or more aspects of the present invention. The codein combination with the computer system is capable of performing one ormore aspects of the present invention.

Although various embodiments are described above, these are onlyexamples. For example, computing environments of other architectures canincorporate and use one or more aspects of the present invention.Further, vectors of other sizes or other registers may be used, andchanges to the instructions may be made without departing from thespirit of the present invention. Additionally, other instructions may beused in the processing. Further, one or more aspects of the inventionrelating to transforming non-contiguous specifiers to contiguousspecifiers may be used in other contexts. Further, the specifiers may befor other than registers. Other changes are also possible.

Further, other types of computing environments can benefit from one ormore aspects of the present invention. As an example, a data processingsystem suitable for storing and/or executing program code is usable thatincludes at least two processors coupled directly or indirectly tomemory elements through a system bus. The memory elements include, forinstance, local memory employed during actual execution of the programcode, bulk storage, and cache memory which provide temporary storage ofat least some program code in order to reduce the number of times codemust be retrieved from bulk storage during execution.

Input/Output or I/O devices (including, but not limited to, keyboards,displays, pointing devices, DASD, tape, CDs, DVDs, thumb drives andother memory media, etc.) can be coupled to the system either directlyor through intervening I/O controllers. Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodems, and Ethernet cards are just a few of the available types ofnetwork adapters.

Referring to FIG. 13, representative components of a Host Computersystem 5000 to implement one or more aspects of the present inventionare portrayed. The representative host computer 5000 comprises one ormore CPUs 5001 in communication with computer memory (i.e., centralstorage) 5002, as well as I/O interfaces to storage media devices 5011and networks 5010 for communicating with other computers or SANs and thelike. The CPU 5001 is compliant with an architecture having anarchitected instruction set and architected functionality. The CPU 5001may have dynamic address translation (DAT) 5003 for transforming programaddresses (virtual addresses) into real addresses of memory. A DATtypically includes a translation lookaside buffer (TLB) 5007 for cachingtranslations so that later accesses to the block of computer memory 5002do not require the delay of address translation. Typically, a cache 5009is employed between computer memory 5002 and the processor 5001. Thecache 5009 may be hierarchical having a large cache available to morethan one CPU and smaller, faster (lower level) caches between the largecache and each CPU. In some implementations, the lower level caches aresplit to provide separate low level caches for instruction fetching anddata accesses. In one embodiment, an instruction is fetched from memory5002 by an instruction fetch unit 5004 via a cache 5009. The instructionis decoded in an instruction decode unit 5006 and dispatched (with otherinstructions in some embodiments) to instruction execution unit or units5008. Typically several execution units 5008 are employed, for examplean arithmetic execution unit, a floating point execution unit and abranch instruction execution unit. The instruction is executed by theexecution unit, accessing operands from instruction specified registersor memory as needed. If an operand is to be accessed (loaded or stored)from memory 5002, a load/store unit 5005 typically handles the accessunder control of the instruction being executed. Instructions may beexecuted in hardware circuits or in internal microcode (firmware) or bya combination of both.

As noted, a computer system includes information in local (or main)storage, as well as addressing, protection, and reference and changerecording. Some aspects of addressing include the format of addresses,the concept of address spaces, the various types of addresses, and themanner in which one type of address is translated to another type ofaddress. Some of main storage includes permanently assigned storagelocations. Main storage provides the system with directly addressablefast-access storage of data. Both data and programs are to be loadedinto main storage (from input devices) before they can be processed.

Main storage may include one or more smaller, faster-access bufferstorages, sometimes called caches. A cache is typically physicallyassociated with a CPU or an I/O processor. The effects, except onperformance, of the physical construction and use of distinct storagemedia are generally not observable by the program.

Separate caches may be maintained for instructions and for dataoperands. Information within a cache is maintained in contiguous byteson an integral boundary called a cache block or cache line (or line, forshort). A model may provide an EXTRACT CACHE ATTRIBUTE instruction whichreturns the size of a cache line in bytes. A model may also providePREFETCH DATA and PREFETCH DATA RELATIVE LONG instructions which effectsthe prefetching of storage into the data or instruction cache or thereleasing of data from the cache.

Storage is viewed as a long horizontal string of bits. For mostoperations, accesses to storage proceed in a left-to-right sequence. Thestring of bits is subdivided into units of eight bits. An eight-bit unitis called a byte, which is the basic building block of all informationformats. Each byte location in storage is identified by a uniquenonnegative integer, which is the address of that byte location or,simply, the byte address. Adjacent byte locations have consecutiveaddresses, starting with 0 on the left and proceeding in a left-to-rightsequence. Addresses are unsigned binary integers and are 24, 31, or 64bits.

Information is transmitted between storage and a CPU or a channelsubsystem one byte, or a group of bytes, at a time. Unless otherwisespecified, in, for instance, the z/Architecture, a group of bytes instorage is addressed by the leftmost byte of the group. The number ofbytes in the group is either implied or explicitly specified by theoperation to be performed. When used in a CPU operation, a group ofbytes is called a field. Within each group of bytes, in, for instance,the z/Architecture, bits are numbered in a left-to-right sequence. Inthe z/Architecture, the leftmost bits are sometimes referred to as the“high-order” bits and the rightmost bits as the “low-order” bits. Bitnumbers are not storage addresses, however. Only bytes can be addressed.To operate on individual bits of a byte in storage, the entire byte isaccessed. The bits in a byte are numbered 0 through 7, from left toright (in, e.g., the z/Architecture). The bits in an address may benumbered 8-31 or 40-63 for 24-bit addresses, or 1-31 or 33-63 for 31-bitaddresses; they are numbered 0-63 for 64-bit addresses. Within any otherfixed-length format of multiple bytes, the bits making up the format areconsecutively numbered starting from 0. For purposes of error detection,and in preferably for correction, one or more check bits may betransmitted with each byte or with a group of bytes. Such check bits aregenerated automatically by the machine and cannot be directly controlledby the program. Storage capacities are expressed in number of bytes.When the length of a storage-operand field is implied by the operationcode of an instruction, the field is said to have a fixed length, whichcan be one, two, four, eight, or sixteen bytes. Larger fields may beimplied for some instructions. When the length of a storage-operandfield is not implied but is stated explicitly, the field is said to havea variable length. Variable-length operands can vary in length byincrements of one byte (or with some instructions, in multiples of twobytes or other multiples). When information is placed in storage, thecontents of only those byte locations are replaced that are included inthe designated field, even though the width of the physical path tostorage may be greater than the length of the field being stored.

Certain units of information are to be on an integral boundary instorage. A boundary is called integral for a unit of information whenits storage address is a multiple of the length of the unit in bytes.Special names are given to fields of 2, 4, 8, and 16 bytes on anintegral boundary. A halfword is a group of two consecutive bytes on atwo-byte boundary and is the basic building block of instructions. Aword is a group of four consecutive bytes on a four-byte boundary. Adoubleword is a group of eight consecutive bytes on an eight-byteboundary. A quadword is a group of 16 consecutive bytes on a 16-byteboundary. When storage addresses designate halfwords, words,doublewords, and quadwords, the binary representation of the addresscontains one, two, three, or four rightmost zero bits, respectively.Instructions are to be on two-byte integral boundaries. The storageoperands of most instructions do not have boundary-alignmentrequirements.

On devices that implement separate caches for instructions and dataoperands, a significant delay may be experienced if the program storesinto a cache line from which instructions are subsequently fetched,regardless of whether the store alters the instructions that aresubsequently fetched.

In one embodiment, the invention may be practiced by software (sometimesreferred to licensed internal code, firmware, micro-code, milli-code,pico-code and the like, any of which would be consistent with one ormore aspects the present invention). Referring to FIG. 13, softwareprogram code which embodies one or more aspects of the present inventionmay be accessed by processor 5001 of the host system 5000 from long-termstorage media devices 5011, such as a CD-ROM drive, tape drive or harddrive. The software program code may be embodied on any of a variety ofknown media for use with a data processing system, such as a diskette,hard drive, or CD-ROM. The code may be distributed on such media, or maybe distributed to users from computer memory 5002 or storage of onecomputer system over a network 5010 to other computer systems for use byusers of such other systems.

The software program code includes an operating system which controlsthe function and interaction of the various computer components and oneor more application programs. Program code is normally paged fromstorage media device 5011 to the relatively higher-speed computerstorage 5002 where it is available for processing by processor 5001. Thetechniques and methods for embodying software program code in memory, onphysical media, and/or distributing software code via networks are wellknown and will not be further discussed herein. Program code, whencreated and stored on a tangible medium (including but not limited toelectronic memory modules (RAM), flash memory, Compact Discs (CDs),DVDs, Magnetic Tape and the like is often referred to as a “computerprogram product”. The computer program product medium is typicallyreadable by a processing circuit preferably in a computer system forexecution by the processing circuit.

FIG. 14 illustrates a representative workstation or server hardwaresystem in which one or more aspects of the present invention may bepracticed. The system 5020 of FIG. 14 comprises a representative basecomputer system 5021, such as a personal computer, a workstation or aserver, including optional peripheral devices. The base computer system5021 includes one or more processors 5026 and a bus employed to connectand enable communication between the processor(s) 5026 and the othercomponents of the system 5021 in accordance with known techniques. Thebus connects the processor 5026 to memory 5025 and long-term storage5027 which can include a hard drive (including any of magnetic media,CD, DVD and Flash Memory for example) or a tape drive for example. Thesystem 5021 might also include a user interface adapter, which connectsthe microprocessor 5026 via the bus to one or more interface devices,such as a keyboard 5024, a mouse 5023, a printer/scanner 5030 and/orother interface devices, which can be any user interface device, such asa touch sensitive screen, digitized entry pad, etc. The bus alsoconnects a display device 5022, such as an LCD screen or monitor, to themicroprocessor 5026 via a display adapter.

The system 5021 may communicate with other computers or networks ofcomputers by way of a network adapter capable of communicating 5028 witha network 5029. Example network adapters are communications channels,token ring, Ethernet or modems. Alternatively, the system 5021 maycommunicate using a wireless interface, such as a CDPD (cellular digitalpacket data) card. The system 5021 may be associated with such othercomputers in a Local Area Network (LAN) or a Wide Area Network (WAN), orthe system 5021 can be a client in a client/server arrangement withanother computer, etc. All of these configurations, as well as theappropriate communications hardware and software, are known in the art.

FIG. 15 illustrates a data processing network 5040 in which one or moreaspects of the present invention may be practiced. The data processingnetwork 5040 may include a plurality of individual networks, such as awireless network and a wired network, each of which may include aplurality of individual workstations 5041, 5042, 5043, 5044.Additionally, as those skilled in the art will appreciate, one or moreLANs may be included, where a LAN may comprise a plurality ofintelligent workstations, coupled to a host processor.

Still referring to FIG. 15, the networks may also include mainframecomputers or servers, such as a gateway computer (client server 5046) orapplication server (remote server 5048 which may access a datarepository and may also be accessed directly from a workstation 5045). Agateway computer 5046 serves as a point of entry into each individualnetwork. A gateway is needed when connecting one networking protocol toanother. The gateway 5046 may be preferably coupled to another network(the Internet 5047 for example) by means of a communications link. Thegateway 5046 may also be directly coupled to one or more workstations5041, 5042, 5043, 5044 using a communications link. The gateway computermay be implemented utilizing an IBM eServer™ System z server availablefrom International Business Machines Corporation.

Referring concurrently to FIG. 14 and FIG. 15, software programming codewhich may embody one or more aspects of the present invention may beaccessed by the processor 5026 of the system 5020 from long-term storagemedia 5027, such as a CD-ROM drive or hard drive. The softwareprogramming code may be embodied on any of a variety of known media foruse with a data processing system, such as a diskette, hard drive, orCD-ROM. The code may be distributed on such media, or may be distributedto users 5050, 5051 from the memory or storage of one computer systemover a network to other computer systems for use by users of such othersystems.

Alternatively, the programming code may be embodied in the memory 5025,and accessed by the processor 5026 using the processor bus. Suchprogramming code includes an operating system which controls thefunction and interaction of the various computer components and one ormore application programs 5032. Program code is normally paged fromstorage media 5027 to high-speed memory 5025 where it is available forprocessing by the processor 5026. The techniques and methods forembodying software programming code in memory, on physical media, and/ordistributing software code via networks are well known and will not befurther discussed herein. Program code, when created and stored on atangible medium (including but not limited to electronic memory modules(RAM), flash memory, Compact Discs (CDs), DVDs, Magnetic Tape and thelike is often referred to as a “computer program product”. The computerprogram product medium is typically readable by a processing circuitpreferably in a computer system for execution by the processing circuit.

The cache that is most readily available to the processor (normallyfaster and smaller than other caches of the processor) is the lowest (L1or level one) cache and main store (main memory) is the highest levelcache (L3 if there are 3 levels). The lowest level cache is oftendivided into an instruction cache (I-Cache) holding machine instructionsto be executed and a data cache (D-Cache) holding data operands.

Referring to FIG. 16, an exemplary processor embodiment is depicted forprocessor 5026. Typically one or more levels of cache 5053 are employedto buffer memory blocks in order to improve processor performance. Thecache 5053 is a high speed buffer holding cache lines of memory datathat are likely to be used. Typical cache lines are 64, 128 or 256 bytesof memory data. Separate caches are often employed for cachinginstructions than for caching data. Cache coherence (synchronization ofcopies of lines in memory and the caches) is often provided by various“snoop” algorithms well known in the art. Main memory storage 5025 of aprocessor system is often referred to as a cache. In a processor systemhaving 4 levels of cache 5053, main storage 5025 is sometimes referredto as the level 5 (L5) cache since it is typically faster and only holdsa portion of the non-volatile storage (DASD, tape etc) that is availableto a computer system. Main storage 5025 “caches” pages of data paged inand out of the main storage 5025 by the operating system.

A program counter (instruction counter) 5061 keeps track of the addressof the current instruction to be executed. A program counter in az/Architecture processor is 64 bits and can be truncated to 31 or 24bits to support prior addressing limits. A program counter is typicallyembodied in a PSW (program status word) of a computer such that itpersists during context switching. Thus, a program in progress, having aprogram counter value, may be interrupted by, for example, the operatingsystem (context switch from the program environment to the operatingsystem environment). The PSW of the program maintains the programcounter value while the program is not active, and the program counter(in the PSW) of the operating system is used while the operating systemis executing. Typically, the program counter is incremented by an amountequal to the number of bytes of the current instruction. RISC (ReducedInstruction Set Computing) instructions are typically fixed length whileCISC (Complex Instruction Set Computing) instructions are typicallyvariable length. Instructions of the IBM z/Architecture are CISCinstructions having a length of 2, 4 or 6 bytes. The Program counter5061 is modified by either a context switch operation or a branch takenoperation of a branch instruction for example. In a context switchoperation, the current program counter value is saved in the programstatus word along with other state information about the program beingexecuted (such as condition codes), and a new program counter value isloaded pointing to an instruction of a new program module to beexecuted. A branch taken operation is performed in order to permit theprogram to make decisions or loop within the program by loading theresult of the branch instruction into the program counter 5061.

Typically an instruction fetch unit 5055 is employed to fetchinstructions on behalf of the processor 5026. The fetch unit eitherfetches “next sequential instructions”, target instructions of branchtaken instructions, or first instructions of a program following acontext switch. Modern Instruction fetch units often employ prefetchtechniques to speculatively prefetch instructions based on thelikelihood that the prefetched instructions might be used. For example,a fetch unit may fetch 16 bytes of instruction that includes the nextsequential instruction and additional bytes of further sequentialinstructions.

The fetched instructions are then executed by the processor 5026. In anembodiment, the fetched instruction(s) are passed to a dispatch unit5056 of the fetch unit. The dispatch unit decodes the instruction(s) andforwards information about the decoded instruction(s) to appropriateunits 5057, 5058, 5060. An execution unit 5057 will typically receiveinformation about decoded arithmetic instructions from the instructionfetch unit 5055 and will perform arithmetic operations on operandsaccording to the opcode of the instruction. Operands are provided to theexecution unit 5057 preferably either from memory 5025, architectedregisters 5059 or from an immediate field of the instruction beingexecuted. Results of the execution, when stored, are stored either inmemory 5025, registers 5059 or in other machine hardware (such ascontrol registers, PSW registers and the like).

A processor 5026 typically has one or more units 5057, 5058, 5060 forexecuting the function of the instruction. Referring to FIG. 17A, anexecution unit 5057 may communicate with architected general registers5059, a decode/dispatch unit 5056, a load store unit 5060, and other5065 processor units by way of interfacing logic 5071. An execution unit5057 may employ several register circuits 5067, 5068, 5069 to holdinformation that the arithmetic logic unit (ALU) 5066 will operate on.The ALU performs arithmetic operations such as add, subtract, multiplyand divide as well as logical function such as and, or and exclusive-or(XOR), rotate and shift. Preferably the ALU supports specializedoperations that are design dependent. Other circuits may provide otherarchitected facilities 5072 including condition codes and recoverysupport logic for example. Typically the result of an ALU operation isheld in an output register circuit 5070 which can forward the result toa variety of other processing functions. There are many arrangements ofprocessor units, the present description is only intended to provide arepresentative understanding of one embodiment.

An ADD instruction for example would be executed in an execution unit5057 having arithmetic and logical functionality while a floating pointinstruction for example would be executed in a floating point executionhaving specialized floating point capability. Preferably, an executionunit operates on operands identified by an instruction by performing anopcode defined function on the operands. For example, an ADD instructionmay be executed by an execution unit 5057 on operands found in tworegisters 5059 identified by register fields of the instruction.

The execution unit 5057 performs the arithmetic addition on two operandsand stores the result in a third operand where the third operand may bea third register or one of the two source registers. The execution unitpreferably utilizes an Arithmetic Logic Unit (ALU) 5066 that is capableof performing a variety of logical functions such as Shift, Rotate, And,Or and XOR as well as a variety of algebraic functions including any ofadd, subtract, multiply, divide. Some ALUs 5066 are designed for scalaroperations and some for floating point. Data may be Big Endian (wherethe least significant byte is at the highest byte address) or LittleEndian (where the least significant byte is at the lowest byte address)depending on architecture. The IBM z/Architecture is Big Endian. Signedfields may be sign and magnitude, 1's complement or 2's complementdepending on architecture. A 2's complement number is advantageous inthat the ALU does not need to design a subtract capability since eithera negative value or a positive value in 2's complement requires only anaddition within the ALU. Numbers are commonly described in shorthand,where a 12 bit field defines an address of a 4,096 byte block and iscommonly described as a 4 Kbyte (Kilo-byte) block, for example.

Referring to FIG. 17B, branch instruction information for executing abranch instruction is typically sent to a branch unit 5058 which oftenemploys a branch prediction algorithm such as a branch history table5082 to predict the outcome of the branch before other conditionaloperations are complete. The target of the current branch instructionwill be fetched and speculatively executed before the conditionaloperations are complete. When the conditional operations are completedthe speculatively executed branch instructions are either completed ordiscarded based on the conditions of the conditional operation and thespeculated outcome. A typical branch instruction may test conditioncodes and branch to a target address if the condition codes meet thebranch requirement of the branch instruction, a target address may becalculated based on several numbers including ones found in registerfields or an immediate field of the instruction for example. The branchunit 5058 may employ an ALU 5074 having a plurality of input registercircuits 5075, 5076, 5077 and an output register circuit 5080. Thebranch unit 5058 may communicate with general registers 5059, decodedispatch unit 5056 or other circuits 5073, for example.

The execution of a group of instructions can be interrupted for avariety of reasons including a context switch initiated by an operatingsystem, a program exception or error causing a context switch, an I/Ointerruption signal causing a context switch or multi-threading activityof a plurality of programs (in a multi-threaded environment), forexample. Preferably a context switch action saves state informationabout a currently executing program and then loads state informationabout another program being invoked. State information may be saved inhardware registers or in memory for example. State informationpreferably comprises a program counter value pointing to a nextinstruction to be executed, condition codes, memory translationinformation and architected register content. A context switch activitycan be exercised by hardware circuits, application programs, operatingsystem programs or firmware code (microcode, pico-code or licensedinternal code (LIC)) alone or in combination.

A processor accesses operands according to instruction defined methods.The instruction may provide an immediate operand using the value of aportion of the instruction, may provide one or more register fieldsexplicitly pointing to either general purpose registers or specialpurpose registers (floating point registers for example). Theinstruction may utilize implied registers identified by an opcode fieldas operands. The instruction may utilize memory locations for operands.A memory location of an operand may be provided by a register, animmediate field, or a combination of registers and immediate field asexemplified by the z/Architecture long displacement facility wherein theinstruction defines a base register, an index register and an immediatefield (displacement field) that are added together to provide theaddress of the operand in memory for example. Location herein typicallyimplies a location in main memory (main storage) unless otherwiseindicated.

Referring to FIG. 17C, a processor accesses storage using a load/storeunit 5060. The load/store unit 5060 may perform a load operation byobtaining the address of the target operand in memory 5053 and loadingthe operand in a register 5059 or another memory 5053 location, or mayperform a store operation by obtaining the address of the target operandin memory 5053 and storing data obtained from a register 5059 or anothermemory 5053 location in the target operand location in memory 5053. Theload/store unit 5060 may be speculative and may access memory in asequence that is out-of-order relative to instruction sequence, howeverthe load/store unit 5060 is to maintain the appearance to programs thatinstructions were executed in order. A load/store unit 5060 maycommunicate with general registers 5059, decode/dispatch unit 5056,cache/memory interface 5053 or other elements 5083 and comprises variousregister circuits, ALUs 5085 and control logic 5090 to calculate storageaddresses and to provide pipeline sequencing to keep operationsin-order. Some operations may be out of order but the load/store unitprovides functionality to make the out of order operations to appear tothe program as having been performed in order, as is well known in theart.

Preferably addresses that an application program “sees” are oftenreferred to as virtual addresses. Virtual addresses are sometimesreferred to as “logical addresses” and “effective addresses”. Thesevirtual addresses are virtual in that they are redirected to physicalmemory location by one of a variety of dynamic address translation (DAT)technologies including, but not limited to, simply prefixing a virtualaddress with an offset value, translating the virtual address via one ormore translation tables, the translation tables preferably comprising atleast a segment table and a page table alone or in combination,preferably, the segment table having an entry pointing to the pagetable. In the z/Architecture, a hierarchy of translation is providedincluding a region first table, a region second table, a region thirdtable, a segment table and an optional page table. The performance ofthe address translation is often improved by utilizing a translationlookaside buffer (TLB) which comprises entries mapping a virtual addressto an associated physical memory location. The entries are created whenthe DAT translates a virtual address using the translation tables.Subsequent use of the virtual addresscan then utilize the entry of thefast TLB rather than the slow sequential translation table accesses. TLBcontent may be managed by a variety of replacement algorithms includingLRU (Least Recently used).

In the case where the processor is a processor of a multi-processorsystem, each processor has responsibility to keep shared resources, suchas I/O, caches, TLBs and memory, interlocked for coherency. Typically,“snoop” technologies will be utilized in maintaining cache coherency. Ina snoop environment, each cache line may be marked as being in any oneof a shared state, an exclusive state, a changed state, an invalid stateand the like in order to facilitate sharing.

I/O units 5054 (FIG. 16) provide the processor with means for attachingto peripheral devices including tape, disc, printers, displays, andnetworks for example. I/O units are often presented to the computerprogram by software drivers. In mainframes, such as the System z fromIBM®, channel adapters and open system adapters are I/O units of themainframe that provide the communications between the operating systemand peripheral devices.

Further, other types of computing environments can benefit from one ormore aspects of the present invention. As an example, an environment mayinclude an emulator (e.g., software or other emulation mechanisms), inwhich a particular architecture (including, for instance, instructionexecution, architected functions, such as address translation, andarchitected registers) or a subset thereof is emulated (e.g., on anative computer system having a processor and memory). In such anenvironment, one or more emulation functions of the emulator canimplement one or more aspects of the present invention, even though acomputer executing the emulator may have a different architecture thanthe capabilities being emulated. As one example, in emulation mode, thespecific instruction or operation being emulated is decoded, and anappropriate emulation function is built to implement the individualinstruction or operation.

In an emulation environment, a host computer includes, for instance, amemory to store instructions and data; an instruction fetch unit tofetch instructions from memory and to optionally, provide localbuffering for the fetched instruction; an instruction decode unit toreceive the fetched instructions and to determine the type ofinstructions that have been fetched; and an instruction execution unitto execute the instructions. Execution may include loading data into aregister from memory; storing data back to memory from a register; orperforming some type of arithmetic or logical operation, as determinedby the decode unit. In one example, each unit is implemented insoftware. For instance, the operations being performed by the units areimplemented as one or more subroutines within emulator software.

More particularly, in a mainframe, architected machine instructions areused by programmers, usually today “C” programmers, often by way of acompiler application. These instructions stored in the storage mediummay be executed natively in a z/Architecture IBM® Server, oralternatively in machines executing other architectures. They can beemulated in the existing and in future IBM® mainframe servers and onother machines of IBM® (e.g., Power Systems servers and System x®Servers). They can be executed in machines running Linux on a widevariety of machines using hardware manufactured by IBM®, Intel®, AMD™,and others. Besides execution on that hardware under a z/Architecture,Linux can be used as well as machines which use emulation by Hercules,UMX, or FSI (Fundamental Software, Inc), where generally execution is inan emulation mode. In emulation mode, emulation software is executed bya native processor to emulate the architecture of an emulated processor.

The native processor typically executes emulation software comprisingeither firmware or a native operating system to perform emulation of theemulated processor. The emulation software is responsible for fetchingand executing instructions of the emulated processor architecture. Theemulation software maintains an emulated program counter to keep trackof instruction boundaries. The emulation software may fetch one or moreemulated machine instructions at a time and convert the one or moreemulated machine instructions to a corresponding group of native machineinstructions for execution by the native processor. These convertedinstructions may be cached such that a faster conversion can beaccomplished. Notwithstanding, the emulation software is to maintain thearchitecture rules of the emulated processor architecture so as toassure operating systems and applications written for the emulatedprocessor operate correctly. Furthermore, the emulation software is toprovide resources identified by the emulated processor architectureincluding, but not limited to, control registers, general purposeregisters, floating point registers, dynamic address translationfunction including segment tables and page tables for example, interruptmechanisms, context switch mechanisms, Time of Day (TOD) clocks andarchitected interfaces to I/O subsystems such that an operating systemor an application program designed to run on the emulated processor, canbe run on the native processor having the emulation software.

A specific instruction being emulated is decoded, and a subroutine iscalled to perform the function of the individual instruction. Anemulation software function emulating a function of an emulatedprocessor is implemented, for example, in a “C” subroutine or driver, orsome other method of providing a driver for the specific hardware aswill be within the skill of those in the art after understanding thedescription of the preferred embodiment. Various software and hardwareemulation patents including, but not limited to U.S. Pat. No. 5,551,013,entitled “Multiprocessor for Hardware Emulation”, by Beausoleil et al.;and U.S. Pat. No. 6,009,261, entitled “Preprocessing of Stored TargetRoutines for Emulating Incompatible Instructions on a Target Processor”,by Scalzi et al; and U.S. Pat. No. 5,574,873, entitled “Decoding GuestInstruction to Directly Access Emulation Routines that Emulate the GuestInstructions”, by Davidian et al; and U.S. Pat. No. 6,308,255, entitled“Symmetrical Multiprocessing Bus and Chipset Used for CoprocessorSupport Allowing Non-Native Code to Run in a System”, by Gorishek et al;and U.S. Pat. No. 6,463,582, entitled “Dynamic Optimizing Object CodeTranslator for Architecture Emulation and Dynamic Optimizing Object CodeTranslation Method”, by Lethin et al; and U.S. Pat. No. 5,790,825,entitled “Method for Emulating Guest Instructions on a Host ComputerThrough Dynamic Recompilation of Host Instructions”, by Eric Traut, eachof which is hereby incorporated herein by reference in its entirety; andmany others, illustrate a variety of known ways to achieve emulation ofan instruction format architected for a different machine for a targetmachine available to those skilled in the art.

In FIG. 18, an example of an emulated host computer system 5092 isprovided that emulates a host computer system 5000′ of a hostarchitecture. In the emulated host computer system 5092, the hostprocessor (CPU) 5091 is an emulated host processor (or virtual hostprocessor) and comprises an emulation processor 5093 having a differentnative instruction set architecture than that of the processor 5091 ofthe host computer 5000′. The emulated host computer system 5092 hasmemory 5094 accessible to the emulation processor 5093. In the exampleembodiment, the memory 5094 is partitioned into a host computer memory5096 portion and an emulation routines 5097 portion. The host computermemory 5096 is available to programs of the emulated host computer 5092according to host computer architecture. The emulation processor 5093executes native instructions of an architected instruction set of anarchitecture other than that of the emulated processor 5091, the nativeinstructions obtained from emulation routines memory 5097, and mayaccess a host instruction for execution from a program in host computermemory 5096 by employing one or more instruction(s) obtained in asequence & access/decode routine which may decode the hostinstruction(s) accessed to determine a native instruction executionroutine for emulating the function of the host instruction accessed.Other facilities that are defined for the host computer system 5000′architecture may be emulated by architected facilities routines,including such facilities as general purpose registers, controlregisters, dynamic address translation and I/O subsystem support andprocessor cache, for example. The emulation routines may also takeadvantage of functions available in the emulation processor 5093 (suchas general registers and dynamic translation of virtual addresses) toimprove performance of the emulation routines. Special hardware andoff-load engines may also be provided to assist the processor 5093 inemulating the function of the host computer 5000′.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising”, when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of one or more aspects of the present inventionhas been presented for purposes of illustration and description, but isnot intended to be exhaustive or limited to the invention in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the invention. The embodiment was chosen and described in order tobest explain the principles of the invention and the practicalapplication, and to enable others of ordinary skill in the art tounderstand the invention for various embodiments with variousmodifications as are suited to the particular use contemplated.

Chapter 23. Vector String Instructions

Vector String Facility

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Instructions

Unless otherwise specified all operands are vector-register operands. A“V” in the assembler syntax designates a vector operand.

Op- Name Mnemonic Characteristics code Page VECTOR FIND ANY VFAE VRR-bo⁹ SP Dv E782 23-1 EQUAL C* VF VECTOR FIND VFEE VRR-b o⁹ SP Dv E780 23-2ELEMENT EQUAL C* VF VECTOR FIND VFENE VRR-b o⁹ SP Dv E781 23-3 ELEMENTNOT C* VF EQUAL VECTOR STRING VSTRC VRR-d o⁹ SP Dv E78A 23-4 RANGECOMPARE C* VF

Proceeding from left to right, every unsigned binary integer element ofthe second operand is compared for equality with each unsigned binaryinteger element of the third operand and optionally zero if the ZeroSearch flag is set in the M₅ field.

If the Result Type (RT) flag in the M₅ field is zero, then for eachelement in the second operand that matches any element in the thirdoperand, or optionally zero, the bit positions of the correspondingelement in the first operand are set to ones, otherwise they are set tozero.

If the Result Type (RT) flag in the M₅ field is one, then the byte indexof the leftmost element in the second operand that matches an element inthe third operand or zero is stored in byte seven of the first operand.

Each instruction has an Extended Mnemonic section which describerecommended extended mnemonics and their corresponding machine assemblersyntax.

Programming Note:

For all instructions that optionally set the condition code, performancemay be degraded if the condition code is set.

If the result Type (RT) flag in the M₅ field is one and no bytes arefound to be equal, or zero if the zero search flag is set, an indexequal to the number of bytes in the vector is stored in byte seven ofthe first operand.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₅ field has the following format:

The bits of the M₅ field are defined as follows:

-   -   Result Type (RT): If zero, each resulting element is a mask of        all range comparisons on that element. If one, a byte index is        stored into byte seven of the first operand and zeros are stored        in all other elements.    -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code is not set        and remains unchanged. If one, the condition code is set as        specified in the following section.        Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M4 field contains a value from 3-15.

2. Bit 0 of the M5 field are not zero.

Resulting Condition Code:

If the CC flag is zero, the code remains unchanged.

If the CC flag is one, the code is set as follows:

0 If the ZS-bit is set, there were no matches in a lower indexed elementthan zero in the second operand. 1 Some elements of the second operandmatch at least one element in the third operand 2 All elements of thesecond operand matched at least one element in the third operand 3 Noelements in the second operand match any elements in the third operandProgram Exceptions:

1 Data with DXC FE, Vector Register

-   -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VFAEB V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, M₅ VFAEH V₁, V₂, V₃, M₅ VFAEV₁, V₂, V₃, 1, M₅ VFAEF V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 2, M₅ VFAEBS V₁,V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, (M₅|X′1′) VFAEHS V₁, V₂, V₃, M₅ VFAE V₁,V₂, V₃, 1, (M₅|X′1′) VFAEFS V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 2, (M₅|X′1′)VFAEZB V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, (M₅|X′2′) VFAEZH V₁, V₂, V₃,M₅ VFAE V₁, V₂, V₃, 1, (M₅|X′2′) VFAEZF V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃,2, (M₅|X′2′) VFAEZBS V₁, V₂, V₃, M₅ VFAE V₁, V₂, V₃, 0, (M₅|X′3′)VFAEZHS V₁, V₂, V₃, M₅ VFAE V₁, V2, V3, 1, (M₅|X′3′) VFAEZFS V₁, V₂, V₃,M₅ VFAE V₁, V₂, V₃, 2, (M₅|X′3′)

Proceeding from left to right, the unsigned binary integer elements ofthe second operand are compared with the corresponding unsigned binaryinteger elements of the third operand. If two elements are equal, thebyte index of the first byte of the leftmost equal element is placed inbyte seven of the first operand. Zeros are stored in the remaining bytesof the first operand. If no bytes are found to be equal, or zero if thezero compare is set, then an index equal to the number of bytes in thevector is stored in byte seven of the first operand. Zeros are stored inthe remaining bytes.

If the Zero Search (ZS) bit is set in the M₅ field, then each element inthe second operand is also compared for equality with zero. If a zeroelement is found in the second operand before any other elements of thesecond and third operands are found to be equal, the byte index of thefirst byte of the element found to be zero is stored in byte seven thefirst operand and zeros are stored in all other byte locations. If theCondition Code Set (CC) flag is one, then the condition code is set tozero.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₅ field has the following format:

The bits of the M₅ field are defined as follows:

-   -   Reserved: Bits 0-1 are reserved and must be zero. Otherwise, a        specification exception is recognized.    -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code remains        unchanged. If one, the condition code is set as specified in the        following section.        Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

2. Bits 0-1 of the M5 field are not zero.

Resulting Condition Code:

If bit 3 of the M₅ field is set to one, the code is set as follows:

0 If the zero compare bit is set, comparison detected a zero element inthe second operand in an element with a smaller index than any equalcomparisons. 1 Comparison detected a match between the second and thirdoperands in some element. If the zero compare bit is set, this matchoccurred in an element with an index less than or equal to the zerocomparing element. 2 — 3 No elements compared equal.

If bit 3 of the M₅ field is zero, the code remains unchanged.

Program Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VFEEB V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 0, M₅ VFEEH V₁, V₂, V₃, M₅ VFEEV₁, V₂, V₃, 1, M₅ VFEEF V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 0, (M₅|X′1′)VFEEHS V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 1, (M₅|X′1′) VFEEFS V₁, V₂, V₃,M₅ VFEE V₁, V₂, V₃, 2, (M₅|X′1′) VFEEZB V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃,0, (M₅|X′2′) VFEEZH V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 1, (M₅|X′2′) VFEEZFV₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 2, (M₅|X′2′) VFEEZBS V₁, V₂, V₃, M₅ VFEEV₁, V₂, V₃, 0, (M₅|X′3′) VFEEZHS V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 1,(M₅|X′3′) VFEEZFS V₁, V₂, V₃, M₅ VFEE V₁, V₂, V₃, 2, (M₅|X′3′)Programming Notes:

1. A byte index is always stored into the first operand for any elementsize. For example, if the element size was set to halfword and the2^(nd) indexed halfword compared equal, then a byte index of 4 would bestored.

2. The third operand should not contain elements with a value of zero.If the third operand does contain a zero and it matches with a zeroelement in the second operand before any other equal comparisons,condition code one is set regardless of the zero compare bit setting.

Proceeding from left to right, the unsigned binary integer elements ofthe second operand are compared with the corresponding unsigned binaryinteger elements of the third operand. If two elements are not equal,the byte index of the left-most non-equal element is placed in byteseven of the first operand and zeros are stored to all other bytes. Ifthe Condition Code Set (CC) bit in the M₅ field is set to one, thecondition code is set to indicate which operand was greater. If allelements were equal, then abyte index equal to the vector size is placedin byte seven of the first operand and zeros are placed in all otherbyte locations. If the CC bit is one, condition code three is set.

If the zero search (ZS) bit is set in the M₅ field, each element in thesecond operand is also compared for equality with zero. If a zeroelement is found in the second operand before any other element of thesecond operand are found to be unequal, the byte index of the first byteof the element fount to be zero is stored in byte seven of the firstoperand. Zeros are stored in all other bytes and condition code 0 isset.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₅ field has the following format:

The bits of the M₅ field are defined as follows:

-   -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code is not set        and remains unchanged. If one, the condition code is set as        specified in the following section.        Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

2. Bits 0-1 of the M₅ field are not zero.

Resulting Condition Code:

If bit 3 of the M₅ field is set to one, the code is set as follows:

0 If the zero, compare bit is set, comparison detected a zero element inboth operands in a lower indexed element than any unequal compares 1 Anelement mismatch was detected and the element in VR2 is less than theelement in VR3 2 An element mismatch was detected and the element in VR2is greater than the element in VR3 3 All elements compared equal, and ifthe zero compare bit is set, no zero elements were found in the secondoperand.

If bit 3 of the M₅ field is zero, the code remains unchanged.

Program Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VFENEB V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 0, M₅ VFENEH V₁, V₂, V₃, M₅VFENE V₁, V₂, V₃, 1, M₅ VFENEF V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 2, M₅VFENEBS V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 0, (M₅|X′1′) VFENEHS V₁, V₂,V₃, M₅ VFENE V₁, V₂, V₃, 1, (M₅|X′1′) VFENEFS V₁, V₂, V₃, M₅ VFENE V₁,V₂, V₃, 2, (M₅|X′1′) VFENEZB V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 0,(M₅|X′2′) VFENEZH V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 1, (M₅|X′2′) VFENEZFV₁, V₂, V₃, M₅ VFENE V1, V2, V3, 2, (M₅|X′2′) VFENEZBS V₁, V₂, V₃, M₅VFENE V₁, V₂, V₃, 0, (M₅|X′3′) VFENEZHS V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃,1, (M₅|X′3′) VFENEZFS V₁, V₂, V₃, M₅ VFENE V₁, V₂, V₃, 2, (M₅|X′3′)

Proceeding from left to right, the unsigned binary integer elements inthe second operand are compared to ranges of values defined by even-oddpairs of elements in the third and fourth operands. The combined withcontrol values from the fourth operand define the range of comparisonsto be performed. If an element matches any of the ranges specified bythe third and fourth operands, it is considered to be a match.

If the Result Type (RT) flag in the M₆ field is zero, the bit positionsof the element in the first operand corresponding to the element beingcompared in the second operand are set to one if the element matches anyof the ranges, otherwise they are set to zero.

If the Result Type (RT) flag in the M6 field is set to one, the byteindex of the first element in the second operand that matches any of theranges specified by the third and fourth operands or a zero comparison,if the ZS flag is set to one, is placed in byte seven of the firstoperand and zeros are stored in the remaining bytes. If no elementsmatch, then an index equal to the number of bytes in a vector is placedin byte seven of the first operand and zeros are stored in the remainingbytes.

The Zero Search (ZS) flag in the M₆ field, if set to one, will add acomparison to zero of the second operand elements to the ranges providedby the third and fourth operands. If a zero comparison in a lowerindexed element than any other true comparison, then the condition codeis set to zero.

The operands contain elements of the size specified by the Element Sizecontrol in the M₅ field.

The fourth operand elements have the following format:

If ES equals 0:

If ES equals 1:

If ES equals 2:

The bits in the fourth operand elements are defined as follows:

-   -   Equal (EQ): When one a comparison for equality is made.    -   Greater Than (GT): When one a greater than comparison is        performed.    -   Less Than (LT): When one a less than comparison is performed.    -   All other bits are reserved and should be zero to ensure future        compatibility.

The control bits may be used in any combination. If none of the bits areset, the comparison will always produce a false result. If all of thebits are set, the comparison will always produce a true result.

The M₅ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3-15—Reserved

The M₆ field has the following format:

The bits of the M₆ field are defined as follows:

-   -   Invert Result (IN): If zero, the comparison proceeds with the        pair of values in the control vector. If one, the result of the        pairs of the comparisons in the ranges are inverted.    -   Result Type (RT): If zero, each resulting element is a mask of        all range comparisons on that element. If one, an index is        stored into byte seven of the first operand. Zeroes are stored        in the remaining bytes.    -   Zero Search (ZS): If one, each element of the second operand is        also compared to zero.    -   Condition Code Set (CC): If zero, the condition code is not set        and remains unchanged. If one, the condition code is set as        specified in the following section.        Special Conditions

A specification exception is recognized and no other action is taken ifany of the following occurs:

1. The M₄ field contains a value from 3-15.

Resulting Condition Code:

0 If ZS = 1 and a zero is found in a lower indexed element than anycompare 1 Comparison found 2 — 3 No comparison foundProgram Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VSTRCB V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 0, M₆ VSTRCH V₁, V₂, V₃,V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 1, M₆ VSTRCF V₁, V₂, V₃, V₄, M₆ VSTRC V₁,V₂, V₃, V₄, 2, M₆ VSTRCBS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 0,(M₆|X′1′) VSTRCHS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 1, (M₆|X′1′)VSTRCFS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 2, (M₆|X′1′) VSTRCZBV₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 0, (M₆|X′2′) VSTRCZH V₁, V₂,V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 1, (M₆|X′2′) VSTRCZF V₁, V₂, V₃, V₄, M₆VSTRC V₁, V₂, V₃, V₄, 2, (M₆|X′2′) VSTRCZBS V₁, V₂, V₃, V₄, M₆ VSTRC V₁,V₂, V₃, V₄, 0, (M₆|X′3′) VSTRCZHS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃,V₄, 1, (M₆|X′3′) VSTRCZFS V₁, V₂, V₃, V₄, M₆ VSTRC V₁, V₂, V₃, V₄, 2,(M₆|X′3′)

FIG. 23-1. ES = 1, ZS = 0 VR1 (a) Results with RT = 0 VR1(b) Resultswith RT = 1

A 32-bit unsigned binary integer containing the number of bytes possibleto load from the second operand location without crossing a specifiedblock boundary, capped at sixteen is placed in the first operand.

The displacement is treated as a 12-bit unsigned integer.

The second operand address is not used to address data.

The M₃ field specifies a code that is used to signal the CPU as to theblock boundary size to compute the number of possible bytes loaded. If areserved value is specified then a specification exception isrecognized.

Code Boundary

0 64-Byte

1 128-Byte

2 256-Byte

3 512-Byte

4 1K-Byte

2K-Byte

6 4K-Byte

7-15 Reserved

Resulting Condition Code:

0 Operand one is sixteen 1 — 2 — 3 Operand one less than sixteenResulting Condition Code:Program Exceptions:

-   -   Operation if the vector-extension facility is not installed    -   Specification

Programming Note:

It is expected that LOAD COUNT TO BLOCK BOUNDARY will be used inconjunction with VECTOR LOAD TO BLOCK BOUNDARY to determine the numberof bytes that were loaded.

The element of the third operand of size specified by the ES value inthe M4 field and indexed by the second operand address is placed in thefirst operand location. The third operand is a vector register. Thefirst operand is a general register. If the index specified by thesecond operand address is greater than the highest numbered element inthe third operand, of the specified element size, the data in the firstoperand is unpredictable.

If the vector register element is smaller than a doubleword, the elementis right aligned in the 64-bit general register and zeros fill theremaining bits.

The second operand address is not used to address data; instead therightmost 12 bits of the address are used to specify the index of anelement within the second operand.

The M₄ field specifies the element size control (ES). The ES controlspecifies the size of the elements in the vector register operands. If areserved value is specified, a specification exception is recognized.

0—Byte

1—Halfword

2—Word

3—Doubleword

4-15—Reserved unchanged.

Resulting Condition Code: The code is unchanged.

Program Exceptions:

-   -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved ES value)    -   Transaction Constraint        Extended Mnemonics:

VLGVB R₁, V₃, D₂(B2) VLGV R1, V3, D2(B2), 0 VLGVH R1, V3, D2(B2) VLGVR1, V3, D2(B2), 1 VLGVF R1, V3, D2(B2) VLGV R1, V3, D2(B2), 2 VLGVG R1,V3, D2(B2) VLGV R1, V3, D2(B2), 3

The first operand is loaded starting at the zero indexed byte elementwith bytes from the second operand. If a boundary condition isencountered, the rest of the first operand is unpredictable. Accessexceptions are not recognized on bytes not loaded.

The displacement for VLBB is treated as a 12-bit unsigned integer.

The M₃ field specifies a code that is used to signal the CPU as to theblock boundary size to load to. If a reserved value is specified, aspecification exception is recognized.

Code Boundary

0 64-Byte

1 128-Byte

2 256-Byte

3 512-Byte

4 1K-Byte

5 2K-Byte

6 4K-Byte

7-15 Reserved

Resulting Condition Code: The code remains unchanged.

Program Exceptions:

-   -   Access (fetch, operand 2)    -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Specification (Reserved Block Boundary Code)    -   Transaction Constraint        Programming Notes:

1. In certain circumstances data may be loaded past the block boundary.However, this will only occur if there are no access exceptions on thatdata.

The 128-bit value in the first operand is stored to the storage locationspecified by the second operand. The displacement for VST is treated asa 12-bit unsigned integer.

Resulting Condition Code: The code remains unchanged.

Program Exceptions:

-   -   Access (store, operand 2)    -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Transaction Constraint

Proceeding from left to right, bytes from the first operand are storedat the second operand location. The general register specified thirdoperand contains a 32-bit unsigned integer containing a value thatrepresents the highest indexed byte to store. If the third operandcontains a value greater than or equal to the highest byte index of thevector, all bytes of the first operand are stored.

Access exceptions are only recognized on bytes stored.

The displacement for VECTOR STORE WITH LENGTH is treated as a 12-bitunsigned integer.

Resulting Condition Code: The condition code remains unchanged.

Program Exceptions:

-   -   Access (store, operand 2)    -   Data with DXC FE, Vector Register    -   Operation if the vector-extension facility is not installed    -   Transaction Constraint        RXB Description

All vector instructions have a field in bits 36-40 of the instructionlabeled as RXB. This field contains the most significant bits for all ofthe vector register designated operands. Bits for register designationsnot specified by the instruction are reserved and should be set to zero;otherwise, the program may not operate compatibly in the future. Themost significant bit is concatenated to the left of the four-bitregister designation to create the five-bit vector register designation.

The bits are defined as follows:

0. Most significant bit for the vector register designation in bits 8-11of the instruction.

1. Most significant bit for the vector register designation in bits12-15 of the instruction.

2. Most significant bit for the vector register designation in bits16-19 of the instruction.

3. Most significant bit for the vector register designation in bits32-35 of the instruction.

Vector Enablement Control

The vector registers and instructions may only be used if both thevector enablement control (bit 46) and the AFP-register-control (bit 45)in control register zero are set to one. If the vector facility isinstalled and a vector instruction is executed without the enablementbits set, a data exception with DXC FE hex is recognized. If the vectorfacility is not installed, an operation exception is recognized.

What is claimed is:
 1. A computer program product for transforminginstruction specifiers of a computing environment, the computer programproduct comprising: a non-transitory computer readable storage mediumreadable by a processing circuit and storing instructions for executionby the processing circuit for performing a method comprising: obtaining,by a processor, from a first instruction defined for a first computerarchitecture, a non-contiguous specifier, the non-contiguous specifierhaving a first portion and a second portion, wherein the obtainingcomprises obtaining the first portion from a first field of theinstruction and the second portion from a second field of theinstruction, the first field separate from the second field; generatinga contiguous specifier using the first portion and the second portion,the generating using one or more rules based on the opcode of the firstinstruction; and using the contiguous specifier to indicate a resourceto be used in execution of a second instruction, the second instructiondefined for a second computer architecture different from the firstcomputer architecture and emulating a function of the first instruction.2. The computer program product of claim 1, wherein the processorcomprises an emulator, and wherein the first portion includes a firstone or more bits, and the second portion includes a second one or morebits, and the generating comprises concatenating the second one or morebits with the first one or more bits to form the contiguous specifier,wherein the second one or more bits are the most significant bits of thecontiguous specifier.
 3. The computer program product of claim 2,wherein the first field has an operand position associated therewith,and the second one or more bits are a subset of a plurality of bits ofthe second field, and wherein the obtaining comprises selecting thesecond one or more bits from the plurality of bits of the second fieldbased on the operand position of the first field.
 4. The computerprogram product of claim 3, wherein the operand position of the firstfield is as a first operand, and wherein the second one or more bits areselected from a left-most location of the second field.
 5. The computerprogram product of claim 1, wherein the first field consists of aregister field, the second field consists of an extension field, thefirst portion consists of a plurality of bits from the register field,the second portion consists of a bit from the extension field in alocation of the instruction corresponding to the register field, and thegenerating comprises concatenating the bit from the extension field withthe bits from the register field to provide the contiguous specifier. 6.The computer program product of claim 1, wherein the using thecontiguous specifier to indicate a resource includes using thecontiguous specifier to map to a register to be used by the secondinstruction.
 7. The computer program product of claim 6, wherein theregister mapped to by the contiguous specifier has the same value as thecontiguous specifier.
 8. The computer program product of claim 6,wherein the register mapped to by the contiguous specifier has adifferent value from the contiguous specifier.
 9. The computer programproduct of claim 1, wherein the first computer architecture includes aninstruction set comprising first instructions having register fields toaccess a sub-section of a register space of the first computerarchitecture, and having second instructions having non-contiguousregister fields for accessing the sub-section and remaining subsectionsof the register space, the first instructions precluded from accessingthe remaining subsections.
 10. The computer program product of claim 1,wherein the first field consists of a register field, the second fieldconsists of an extension field, the first portion consists of aplurality of bits from the register field, the second portion consistsof a bit from the extension field in a location of the instructioncorresponding to the register field, and the generating comprisesconcatenating the bit from the extension field with the bits from theregister field to provide the contiguous specifier, and furthercomprising: obtaining, by the processor, from the first instruction,another non-contiguous specifier, the another non-contiguous specifierhaving another first portion and another second portion, wherein theobtaining comprises obtaining the another first portion from anotherfirst field of the instruction and the another second portion fromanother bit of the extension field, the another first field separatefrom the first field and the extension field; generating anothercontiguous specifier using the another first portion and the anotherbit, the generating using one or more rules based on the opcode of thefirst instruction; and using the another contiguous specifier toindicate a resource to be used in execution of the second instruction.11. The computer program product of claim 1, wherein the first computerarchitecture comprises a first instruction set architecture and thefirst instruction is defined for the first instruction set architecture,wherein the second computer architecture comprises a second instructionset architecture and the second instruction is defined for the secondinstruction set architecture, and wherein the second instruction setarchitecture is a different instruction set architecture than the firstinstruction set architecture.
 12. A computer system for transforminginstruction specifiers of a computing environment, the computer systemcomprising: a memory; and a processor in communications with the memory,wherein the computer system is configured to perform a method, saidmethod comprising: obtaining, by a processor, from a first instructiondefined for a first computer architecture, a non-contiguous specifier,the non-contiguous specifier having a first portion and a secondportion, wherein the obtaining comprises obtaining the first portionfrom a first field of the instruction and the second portion from asecond field of the instruction, the first field separate from thesecond field; generating a contiguous specifier using the first portionand the second portion, the generating using one or more rules based onthe opcode of the first instruction; and using the contiguous specifierto indicate a resource to be used in execution of a second instruction,the second instruction defined for a second computer architecturedifferent from the first computer architecture and emulating a functionof the first instruction.
 13. The computer system of claim 12, whereinthe processor comprises an emulator, and wherein the first portionincludes a first one or more bits, and the second portion includes asecond one or more bits, and the generating comprises concatenating thesecond one or more bits with the first one or more bits to form thecontiguous specifier, wherein the second one or more bits are the mostsignificant bits of the contiguous specifier.
 14. The computer system ofclaim 13, wherein the first field has an operand position associatedtherewith, and the second one or more bits are a subset of a pluralityof bits of the second field, and wherein the obtaining comprisesselecting the second one or more bits from the plurality of bits of thesecond field based on the operand position of the first field.
 15. Thecomputer system of claim 14, wherein the operand position of the firstfield is as a first operand, and wherein the second one or more bits areselected from a left-most location of the second field.
 16. The computersystem of claim 12, wherein the first field comprises a register field,the second field comprises an extension field, the first portioncomprises a plurality of bits from the register field, the secondportion comprises a bit from the extension field in a locationcorresponding to the register field, and the generating comprisesconcatenating the bit from the extension field with the bits from theregister field to provide the contiguous specifier.
 17. The computersystem of claim 12, wherein the using the contiguous specifier toindicate a resource includes using the contiguous specifier to map to aregister to be used by the second instruction.
 18. The computer systemof claim 17, wherein the register mapped to by the contiguous specifierhas one of: the same value as the contiguous specifier or has adifferent value from the contiguous specifier.
 19. The computer systemof claim 12, wherein the first computer architecture comprises a firstinstruction set architecture and the first instruction is defined forthe first instruction set architecture, wherein the second computerarchitecture comprises a second instruction set architecture and thesecond instruction is defined for the second instruction setarchitecture, and wherein the second instruction set architecture is adifferent instruction set architecture than the first instruction setarchitecture.